The shifted balance of arginine metabolites in acute myocardial infarction patients and its clinical relevance

The arginine metabolism as a target for cardioprotection in patients with ST-segment elevation myocardial infarction (STEMI) remains insufficiently understood. Arginine, ornithine, citrulline, asymmetric dimethylarginine (ADMA) and proline plasma levels were measured using liquid chromatography and tandem mass spectrometry in 70 consecutive STEMI patients upon admission and at 6-month follow-up and were compared with left ventricular function, volumes, and infarct characteristics determined by cardiac magnetic resonance imaging, and with 5-year clinical outcomes. Baseline median concentration of arginine was higher by 49% (P=0.002) when compared to 6-month measurements and was correlated with an ischemia risk area (R=0.34, P=0.004) and infarct size (R=0.33, P=0.006). Following ischemia median citrulline/arginine index decreased when compared with 6-month result (P=0.002), while citrulline/ornithine and arginine/ADMA ratios maintained unchanged indicating a shift of arginine metabolism from nitric oxide synthase (NOS) towards arginase. The 6-month arginine concentration reached the area under the ROC curve of 0.67 (95% confidence interval 0.54-0.81) for prediction of death, myocardial infarction or heart failure hospitalization and its value of < 29 mu M was associated with lower event free survival (P=0.02). In STEMI patients, during ischemia conversion of elevated plasma arginine was shifted from NOS towards arginase. Decreased 6-month arginine concentrations were associated with worse long-term outcomes.

Automated summary

In patients with ST-segment elevation myocardial infarction, arginine metabolism shifted from nitric oxide synthase towards arginase during ischemia. Lower arginine concentrations at 6-month follow-up were associated with worse long-term outcomes.